| /* AbstractSelectableChannel.java |
| Copyright (C) 2002, 2003, 2004 Free Software Foundation, Inc. |
| |
| This file is part of GNU Classpath. |
| |
| GNU Classpath is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 2, or (at your option) |
| any later version. |
| |
| GNU Classpath is distributed in the hope that it will be useful, but |
| WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with GNU Classpath; see the file COPYING. If not, write to the |
| Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
| 02110-1301 USA. |
| |
| Linking this library statically or dynamically with other modules is |
| making a combined work based on this library. Thus, the terms and |
| conditions of the GNU General Public License cover the whole |
| combination. |
| |
| As a special exception, the copyright holders of this library give you |
| permission to link this library with independent modules to produce an |
| executable, regardless of the license terms of these independent |
| modules, and to copy and distribute the resulting executable under |
| terms of your choice, provided that you also meet, for each linked |
| independent module, the terms and conditions of the license of that |
| module. An independent module is a module which is not derived from |
| or based on this library. If you modify this library, you may extend |
| this exception to your version of the library, but you are not |
| obligated to do so. If you do not wish to do so, delete this |
| exception statement from your version. */ |
| |
| |
| package java.nio.channels.spi; |
| |
| import java.io.IOException; |
| import java.nio.channels.ClosedChannelException; |
| import java.nio.channels.SelectableChannel; |
| import java.nio.channels.SelectionKey; |
| import java.nio.channels.Selector; |
| import java.nio.channels.IllegalBlockingModeException; |
| import java.util.LinkedList; |
| import java.util.ListIterator; |
| |
| public abstract class AbstractSelectableChannel extends SelectableChannel |
| { |
| private boolean blocking = true; |
| private Object LOCK = new Object(); |
| private SelectorProvider provider; |
| private LinkedList keys = new LinkedList(); |
| |
| /** |
| * Initializes the channel |
| * |
| * @param provider the provider that created this channel |
| */ |
| protected AbstractSelectableChannel(SelectorProvider provider) |
| { |
| this.provider = provider; |
| } |
| |
| /** |
| * Retrieves the object upon which the configureBlocking and register |
| * methods synchronize. |
| * |
| * @return the blocking lock |
| */ |
| public final Object blockingLock() |
| { |
| return LOCK; |
| } |
| |
| /** |
| * Adjusts this channel's blocking mode. |
| * |
| * @param blocking true if blocking should be enabled, false otherwise |
| * |
| * @return this channel |
| * |
| * @exception IOException If an error occurs |
| */ |
| public final SelectableChannel configureBlocking(boolean blocking) |
| throws IOException |
| { |
| synchronized (blockingLock()) |
| { |
| if (this.blocking != blocking) |
| { |
| implConfigureBlocking(blocking); |
| this.blocking = blocking; |
| } |
| } |
| |
| return this; |
| } |
| |
| /** |
| * Closes this channel. |
| * |
| * @exception IOException If an error occurs |
| */ |
| protected final void implCloseChannel() throws IOException |
| { |
| implCloseSelectableChannel(); |
| } |
| |
| /** |
| * Closes this selectable channel. |
| * |
| * @exception IOException If an error occurs |
| */ |
| protected abstract void implCloseSelectableChannel() |
| throws IOException; |
| |
| /** |
| * Adjusts this channel's blocking mode. |
| * |
| * @param blocking true if blocking should be enabled, false otherwise |
| * |
| * @exception IOException If an error occurs |
| */ |
| protected abstract void implConfigureBlocking(boolean blocking) |
| throws IOException; |
| |
| /** |
| * Tells whether or not every I/O operation on this channel will block |
| * until it completes. |
| * |
| * @return true of this channel is blocking, false otherwise |
| */ |
| public final boolean isBlocking() |
| { |
| return blocking; |
| } |
| |
| /** |
| * Tells whether or not this channel is currently registered with |
| * any selectors. |
| * |
| * @return true if this channel is registered, false otherwise |
| */ |
| public final boolean isRegistered() |
| { |
| return ! keys.isEmpty(); |
| } |
| |
| /** |
| * Retrieves the key representing the channel's registration with the |
| * given selector. |
| * |
| * @param selector the selector to get a selection key for |
| * |
| * @return the selection key this channel is registered with |
| */ |
| public final SelectionKey keyFor(Selector selector) |
| { |
| if (! isOpen()) |
| return null; |
| |
| try |
| { |
| synchronized (blockingLock()) |
| { |
| return locate(selector); |
| } |
| } |
| catch (Exception e) |
| { |
| return null; |
| } |
| } |
| |
| /** |
| * Returns the provider that created this channel. |
| * |
| * @return the selector provider that created this channel |
| */ |
| public final SelectorProvider provider() |
| { |
| return provider; |
| } |
| |
| private SelectionKey locate(Selector selector) |
| { |
| ListIterator it = keys.listIterator(); |
| |
| while (it.hasNext()) |
| { |
| SelectionKey key = (SelectionKey) it.next(); |
| |
| if (key.selector() == selector) |
| return key; |
| } |
| |
| return null; |
| } |
| |
| /** |
| * Registers this channel with the given selector, returning a selection key. |
| * |
| * @param selin the seletor to use |
| * @param ops the interested operations |
| * @param att an attachment for the returned selection key |
| * |
| * @return the registered selection key |
| * |
| * @exception ClosedChannelException If the channel is already closed. |
| * @exception IllegalBlockingModeException If the channel is configured in |
| * blocking mode. |
| */ |
| public final SelectionKey register(Selector selin, int ops, Object att) |
| throws ClosedChannelException |
| { |
| if (! isOpen()) |
| throw new ClosedChannelException(); |
| |
| if ((ops & ~validOps()) != 0) |
| throw new IllegalArgumentException(); |
| |
| SelectionKey key = null; |
| AbstractSelector selector = (AbstractSelector) selin; |
| |
| synchronized (blockingLock()) |
| { |
| if (blocking) |
| throw new IllegalBlockingModeException(); |
| |
| key = locate(selector); |
| |
| if (key != null && key.isValid()) |
| { |
| if (att != null) |
| key.attach(att); |
| } |
| else |
| { |
| key = selector.register(this, ops, att); |
| |
| if (key != null) |
| addSelectionKey(key); |
| } |
| } |
| |
| return key; |
| } |
| |
| void addSelectionKey(SelectionKey key) |
| { |
| keys.add(key); |
| } |
| |
| // This method gets called by AbstractSelector.deregister(). |
| void removeSelectionKey(SelectionKey key) |
| { |
| keys.remove(key); |
| } |
| } |